如何在Bash中替换任意长度的重复字符序列？

需要处理带已知分隔符的字符串，把出现一次或多次的相同字符序列（这里是*）替换成单个指定字符（比如_），无需假设重复序列的最大长度。

原有方案的问题 #

之前的做法是多次调用sed，逐个替换不同长度的*组合，必须提前预估最大重复长度，扩展性极差：

cat example_file.txt | sed 's/\*\*\*\*\*\*\*\*/_/g' | sed 's/\*\*\*\*\*\*\*/_/g' | sed 's/\*\*\*\*\*\*/_/g' | sed 's/\*\*\*\*/_/g' | sed 's/\*\*/_/g' | sed 's/\*/_/g' > clean_file.txt

解决方案：用正则匹配任意长度的重复序列 #

直接利用正则表达式匹配一个或多个连续的*，一次完成全局替换，无需考虑重复长度。

方法1：兼容所有sed版本的基础正则语法 #

sed 's/\*\+/_/g' example_file.txt > clean_file.txt

• \*：转义后的星号，匹配单个*字符
• \+：匹配前面的字符（即*）一次或多次（基础正则中需转义+）
• g：全局替换一行内所有匹配的部分

方法2：启用扩展正则（适用于GNU sed等支持-E选项的版本） #

sed -E 's/\*+/\_/g' example_file.txt > clean_file.txt

• -E：启用扩展正则语法，此时+无需转义，直接表示“匹配前面字符一次或多次”

输入输出示例 #

输入文件example_file.txt内容： #

>SH1111056.09FU|KC881085_refs|k__Fungi;p__Ascomycota;c__Sordariomycetes;o__Hypocreales;f__Clavicipitaceae;g__Neotyphodium;s__Neotyphodium_siegelii;|foliar_endophyte*litter_saprotroph*class1_clavicipitaceous_endophyte**leaf/fruit/seed**non-aquatic*arthropod-associated*filamentous_mycelium******
>SH1115797.09FU|UDB031565_refs|k__Fungi;p__Basidiomycota;c__Agaricomycetes;o__Hymenochaetales;f__Hymenochaetaceae;g__Fomitiporia;s__Fomitiporia_hippophaeicola;|plant_pathogen*wood_saprotroph**wood_pathogen*wood*white_rot*non-aquatic**filamentous_mycelium*polyporoid*poroid****
>SH0879139.09FU|KF945456|k__Viridiplantae;p__Anthophyta;c__Eudicotyledonae;o__Lamiales;f__Acanthaceae;g__Ruellia;s__Ruellia_brandbergensis;|ND**************
>SH0991532.09FU|UDB07658019|k__Fungi;p__Ascomycota;c__Dothideomycetes;o__Venturiales;f__Venturiaceae;g__Sympodiella;s__Sympodiella_sp;|litter_saprotroph****leaf/fruit/seed**non-aquatic**filamentous_mycelium******
>SH0991546.09FU|UDB07657573|k__Fungi;p__Ascomycota;c__Dothideomycetes;o__Venturiales;f__Venturiaceae;g__Sympodiella;s__Sympodiella_sp;|litter_saprotroph****leaf/fruit/seed**non-aquatic**filamentous_mycelium******

处理后输出： #

>SH1111056.09FU|KC881085_refs|k__Fungi;p__Ascomycota;c__Sordariomycetes;o__Hypocreales;f__Clavicipitaceae;g__Neotyphodium;s__Neotyphodium_siegelii;|foliar_endophyte_litter_saprotroph_class1_clavicipitaceous_endophyte_leaf/fruit/seed_non-aquatic_arthropod-associated_filamentous_mycelium_
>SH1115797.09FU|UDB031565_refs|k__Fungi;p__Basidiomycota;c__Agaricomycetes;o__Hymenochaetales;f__Hymenochaetaceae;g__Fomitiporia;s__Fomitiporia_hippophaeicola;|plant_pathogen_wood_saprotroph_wood_pathogen_wood_white_rot_non-aquatic_filamentous_mycelium_polyporoid_poroid_
>SH0879139.09FU|KF945456|k__Viridiplantae;p__Anthophyta;c__Eudicotyledonae;o__Lamiales;f__Acanthaceae;g__Ruellia;s__Ruellia_brandbergensis;|ND_
>SH0991532.09FU|UDB07658019|k__Fungi;p__Ascomycota;c__Dothideomycetes;o__Venturiales;f__Venturiaceae;g__Sympodiella;s__Sympodiella_sp;|litter_saprotroph_leaf/fruit/seed_non-aquatic_filamentous_mycelium_
>SH0991546.09FU|UDB07657573|k__Fungi;p__Ascomycota;c__Dothideomycetes;o__Venturiales;f__Venturiaceae;g__Sympodiella;s__Sympodiella_sp;|litter_saprotroph_leaf/fruit/seed_non-aquatic_filamentous_mycelium_

内容的提问来源于stack exchange，提问作者another_rando